The expression “planiform piece” is to be taken as meaning a piece the thickness is very considerably less than the other dimensions, said piece not necessarily being flat but possibly having inwardly and /or outwardly facing deformations.
Although more particularly provided for pieces intended for the interior trim of the bodywork of motor vehicles passenger compartments such as, for example, door panels, cabinet-work or dashboards, the invention can be used in any other field.
At the present time, when it is wished to obtain a piece the contour of which has apices of a particular profile, in particular rounded, use is made of knives corresponding to each of the sides of the piece and all or part of the apices located at each end of the side cut. The knives are actuated simultaneously, in a direction substantially orthogonal to each of the sides. When they are in contact with the piece, their lateral ends are contiguous and in contact, two by two, in the area of a point located along the profile of the apices.
A first drawback of this process is that leads to marking, or even incorrect cutting of the part, owing to unsatisfactory cut joins in the area of the point of contact of the knives. Furthermore, when the knives approach on either side, one observes, at the apices, a pushing back of the parts of the piece to be cut, which can be prejudicial to the definition of the contour and to the cut.